This invention relates generally to processes for manufacturing semiconductor integrated circuits.
Semiconductor integrated circuits undergo a process called contact plug fill. In this process, a dielectric material is processed. Contact holes or trenches are patterned into the dielectric. These holes or trenches are then filled with a conducting fill material to form contact plugs.
In some cases, some of the plugs are well filled with the conducting material, while others may have gaps or seams in them. This is an undesirable feature which may reduce the yield of the resulting semiconductor integrated circuit.
Thus, there is a need for ways to evaluate the quality of the contact plug fill.